High blood pressure can occur in pregnancy in two forms. It may be a preexisting condition, called chronic hypertension, or it can develop during pregnancy--a condition known as gestational hypertension. It is also called toxemia or preeclampsia and occurs most often in young women with a first pregnancy.
AC relays. AC relays are manufactured similar to their DC counterparts. If AC current is applied to a DC relay, the relay will pulse at the frequency of the AC current. To overcome this problem, the core is equipped with a shading ring on one-half of the core (Photo 2).
The Purpose of an Electrical Relay. An electrical relay device refers to a switch that is electrically operated. Relays are used to control the direct output supplied by circuits, and are used in numerous industrial applications. Relays rely on an electromagnet, which pulls the switch mechanism, or lever, moving it to the on or off position based on the level of electromagnetic energy received.